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Enhanced Natural Convection for Accelerating Melting of Phase Change Material in Cellular Structure through Inserting Fin

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Journal of Thermal Science 2024年第2期33卷 548-563页

作者： KONG Dekui zhang yongcun LIU Shutian State Key Laboratory of Structural Analysis Optimization and CAE Software for Industrial EquipmentDalian University of TechnologyDalian116024China

The design of thermal conductivity enhancers(TCE) is quite critical to overcoming the disadvantage of the poor thermal conductivity of phase change materials(PCM).The main contribution of this study is firstly to discuss how to actively enhance natural convection of the melted PCM in cellular structure by the fin formed in the structure under the condition of the same metal mass,apart from simultaneously improving heat conduction,which can boost the heat transfer performance.Also,a tailored hybrid fin-lattice structure(HFS) as TCE is designed and fabricated by additive manufacturing(AM).A two-equation numerical method is applied to study the heat transfer of the PCM,and its feasibility is validated with the experimental data.The numerical results indicate that enhanced natural convection and improved heat conduction can be obtained simultaneously when a well-designed fin is embedded into a lattice structure.The enhanced natural convection results in the improved melting rate and the decreased wall temperature;e.g.,the complete melting time and the wall temperature are reduced by 11.6% and 19.7%,respectively,because of the fin for metal aluminum.Moreover,the parameters of HFS including the porosity,pore density,and fin dimension have a great impact on the heat transfer.The enhancement effect of the fin for HFS on the melting rate of the PCM increases as the thermal conductivity of the base material decreases.For example,when the fin is introduced into the lattice structure,the complete melting time is reduced by 24.1% for metal titanium.In summary,this study enables us to obtain a good understanding of the mechanism of the heat transfer and provides necessary experimental data for the structural design of HFS fabricated by AM.

关键词： natural convection heat transfer enhancement phase change material additive manufacturing hybrid fin-lattice structure

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Enhancing buckling capacity of a rectangular plate under uniaxial compression by utilizing an auxetic material

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Chinese Journal of Aeronautics 2016年第4期29卷 945-951页

作者： zhang yongcun Li Xiaobin Liu Shutian State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology

Auxetic materials have previously been shown to enhance various performances due to its unusual property of becoming fatter when uniaxially stretched and thinner when uniaxially compressed(i.e., the materials exhibit a negative Poisson's ratio). The current study focuses on assessing the potential of an auxetic material to enhance the buckling capacity of a rectangular plate under uniaxial compression. The in-plane translational restraint along the unloaded edges that was often neglected in open literature is taken into consideration in our buckling model proposed in this study. The closed-form expressions for the critical buckling coefficient of the rectangle are provided and the predicted results agree well with those determined by the finite element method. Furthermore, the results indicate that the buckling performance of a rectangular plate under uniaxial compression can be significantly improved by replacing the traditional material that has a positive Poisson's ratio with an auxetic material when there is in-plane translation restraint along the unloaded edges.

关键词： Auxetic material Buckling Elastically restraint Negative Poisson’s ratio Optimization

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Micromechanical mode-localized electric current sensor

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Microsystems & Nanoengineering 2022年第2期8卷 49-58页

作者： Han Li Zhao zhang Luhan Zu yongcun Hao Honglong Chang Ministry of Education Key Laboratory of Micro and Nano Systems for Aerospace School of Mechanical EngineeringNorthwestern Polytechnical University127 Youyi West RoadBeilin DistrictXi'an 710072China

This paper outlines the design of a novel mode-localized electric current sensor based on a mechanically sensitive element of weakly coupled resonator systems.With the advantage of a high voltage sensitivity of weakly coupled resonator systems,the current under test is converted to voltage via a silicon shunt resistor,which causes stiffness perturbation to one resonator.The mode-localization phenomenon alters the energy distribution in the weakly coupled resonator system.A theoretical model of current sensing is established,and the performance of the current sensor is determined:the sensitivity of the electric current sensor is 567/A,the noise floor is 69.3 nAA/Hz,the resolution is 183.6 nA,and the bias instability is 81.6 nA.The mode-localized electric current sensor provides a new approach for measuring sub-microampere currents for applications in nuclear physics,including for photocurrent signals and transistor leakage currents.It could also become a key component of a portable mode-localized multimeter when combined with a mode-localized voltmeter.In addition,it has the potential for use in studying sensor arrays to achieve higher resolution.

关键词： mode weakly resonator

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Double Star TC-1 observation of the earthward flowing plasmoids in the near magnetotail

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Chinese Science Bulletin 2007年第13期52卷 1843-1848页

作者： zhang yongcun LIU ZhenXing SHEN Chao DUAN SuPing HE ZhaoHai C M CARR H REME State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China Graduate University of the Chinese Academy of Sciences Beijing 100049 China The Blackett Laboratory Imperial College London SW7 2BZ UK Centre d'Etudes Spatiale des Rayonnements BP 4346 31028 Toulouse Cedex 4 France

We analyze Double Star TC-1 magnetic field data from July to September in 2004 and find that plas-moids exist in the very near-Earth magnetotail. It is the first time that TC-1 observes the plasmoids inthe magnetotail at X > ?13 RE. According to the difference of the magnetic field structure in plasmoids,we choose two typical cases for our study: the magnetic flux rope on August 6 with the open magneticfield and the magnetic loop on September 14 with the closed magnetic field. Both of the cases are as-sociated with the high speed earthward flow and the magnetic loop is related to a strong substorm. Theions can escape from the magnetic flux rope along its open field line, but the case of the closed mag-netic loop can trap the ions. The earthward flowing plasmoids observed by TC-1 indicate that the mul-tiple X-line magnetic reconnection occurs beyond the distance of X=?10 RE from the earth.

关键词：磁层尾磁线圈焊接磁性

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参数优化方法对微生物模型预测土壤有机碳时空演变的影响

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土壤学报 2024年第1期61卷 39-51页

作者：张秀谢恩泽陈剑彭雨璇严国菁赵永存土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所) 南京210008 中国科学院大学北京100049

准确把握土壤有机碳(SOC)的时空演变规律对于土壤资源的高效持续利用、发挥土壤生态系统服务功能,以及应对气候变化等均具有重要意义。以江苏省南部为研究区,以明确表达微生物分解作用的微生物模型MIMICS为对象,以模型参数敏感性分析为... 详细信息

准确把握土壤有机碳(SOC)的时空演变规律对于土壤资源的高效持续利用、发挥土壤生态系统服务功能,以及应对气候变化等均具有重要意义。以江苏省南部为研究区,以明确表达微生物分解作用的微生物模型MIMICS为对象,以模型参数敏感性分析为切入点,分析了不同参数优化方法对MIMICS模型预测苏南农田表层(0~20 cm)SOC时空演变动态的影响。结果表明,批处理和点对点两种参数优化方法下,MIMICS模型均能较好地模拟1980-2015年苏南农田表层SOC密度先增加后减少的总体趋势;采用考虑模型参数空间异质性的点对点参数优化方法时,MIMICS模型预测精度最高,其预测误差(RMSE)较采用默认参数值时分别降低22.2%(2000年独立验证)和14.7%(2015年独立验证),但2015年SOC密度预测精度依然偏低(R^(2)=0.13,RMSE=1.22kg·m^(-2))。上述结果表明进一步改进微生物模型的结构、提高模型输入数据的精度及分辨率,将是微生物模型建模区域尺度SOC时空动态所面临的重要挑战。

关键词：土壤有机碳微生物模型敏感性分析参数优化

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考虑滚道缺陷的圆柱滚子轴承保持架振动特性

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轴承 2024年第3期 28-35页

作者：张文博杨海生崔永存邓四二尉询楷河南科技大学机电工程学院河南洛阳471003 常州光洋轴承有限公司江苏常州213022 北京航空工程技术研究中心北京100076

基于滚动轴承多体动力学理论,以滚子经过滚道缺陷区域时产生的附加位移表征故障,建立轴承滚道缺陷动力学模型。考虑滚子进出缺陷区域时与滚道间接触载荷的变化,建立圆柱滚子轴承动力学微分方程组并求解,研究滚道缺陷时保持架振动响应规... 详细信息

基于滚动轴承多体动力学理论,以滚子经过滚道缺陷区域时产生的附加位移表征故障,建立轴承滚道缺陷动力学模型。考虑滚子进出缺陷区域时与滚道间接触载荷的变化,建立圆柱滚子轴承动力学微分方程组并求解,研究滚道缺陷时保持架振动响应规律。结果表明:与正常轴承相比,滚道缺陷会导致保持架与滚子间碰撞力增大且接触频率增加,同时保持架打滑率增大;随缺陷宽度增大,内滚道缺陷时保持架振动加速度级逐渐增加,外滚道缺陷时保持架振动加速度级先减小后增加,缺陷宽度大于1 mm后,内滚道缺陷时保持架的振动加速度级明显更大。

关键词：滚动轴承圆柱滚子轴承缺陷动力学模型振动保持架

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Fracture development during disposal of hazardous drilling cuttings by deep underground injection: A review

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Journal of Rock Mechanics and Geotechnical Engineering 2022年第5期14卷 1652-1670页

作者： Shuai zhang yongcun Feng Bin Li Jingen Deng Tie Geng Jincai zhang College of Petroleum Engineering China University of PetroleumBejing102249China State Key Laboratory of Petroleum Resources and and Prospecting China University of PetroleumBeijing102200China Oilflied Chemicals Division China Oilfield Services LimitedLangfang065201China Sinopec Tech Houston HoustonTXUSA

Drilling fluids with complicated compositions are becoming more common as the oil and gas industry develops. The production of hazardous cuttings is increasing, which not only stifles the oil and gas industry’s development but also poses a severe environmental threat. Deep underground re-injection is a cost-effective and efficient method for dealing with hazardous cuttings. Numerous experiments and numerical studies on cuttings re-injection have been conducted in the past thirty years. However, there is still a divergence of views on the fracture development in the process of cuttings re-injection. A comprehensive review of existing studies is necessary to help researchers advance this technology. This paper provides a review of the fundamental studies on fracture behaviors during the deep underground re-injection of drilling cuttings. The limitations of the existing studies are also discussed to inspire new research endeavors.

关键词： Hazardous drilling cuttings Cuttings disposal Cuttings re-injection Fracture development Multiple fractures

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In situ SR-CT Experimental Study on the Directional Sintering of High-Temperature Superconductor YBCO Materials in the Microwave Fields

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Acta Metallurgica Sinica(English Letters) 2022年第1期35卷 67-77页

作者： Liangyuan Wang Lei Shen yongcun Li Yuanjie Wang Yu Xiao Xingyi zhang Feng Xu Xiaofang Hu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsCAS Center for Excellence in Complex System MechanicsUniversity of Science and Technology of ChinaAnhui230027China Key Laboratory of Mechanics on Disaster and Environment in Western China Attached to the Ministry of Education of China Lanzhou UniversityLanzhou730000China Shanxi Key Lab of Material Strength&Structural Impact College of Mechanical and Vehicle EngineeringTaiyuan University of TechnologyTaiyuan030024China

YBa_(2)Cu_(3)O_(7-x)(YBCO)is a kind of high-temperature superconducting material that has important application in information,energy,medical treatment,etc.,and the superconducting properties of YBCO are closely related to its internal microstructure.In this study,the microwave heating method was adopted to prepare the YBCO materials.The internal 3 D online evolution observation based on the synchrotron radiation computed tomography technology shows that there was directional grain growth phenomenon of YBCO during microwave sintering process.In local regions with special microstructure,these particles grew to the same point.Here,the theoretical models of single and multiple particles in the microwave electromagnetic fields were established.Based on these theoretical models and finite element analysis,it shows that the YBCO particles can modulate the distribution of electromagnetic fields,resulting in the significantly higher electric field intensity at the particle junctions than other regions.Moreover,there were very high electric field intensity and temperature gradients in the directions of particle growth.These factors were crucial in directional sintering.These results will provide theoretical basis and technical guidance for the controllable preparation and performance optimization of the internal microstructure of superconducting materials in the preparation process.

关键词： Synchrotron radiation computed tomography Microwave sintering Microstructure In situ

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一种解决压延铜箔电镀后表面粗糙问题的微蚀液

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印制电路信息 2024年第S1期32卷 210-215页

作者：邵永存李晓红宣宇娜章晓冬刘江波广东天承科技股份有限公司广东广州511300 上海天承化学有限公司上海201500

压延铜箔是通过对铜锭的反复轧制-退火工艺而成的,其铜原子呈不规则层状结晶,导致压延铜箔在后续的电镀铜过程中容易产生表面粗糙的问题。压延铜箔通常用于挠性线路板,线路表面越粗糙,则电阻越大,相应的信号延迟越大,信号质量越差。本... 详细信息

压延铜箔是通过对铜锭的反复轧制-退火工艺而成的,其铜原子呈不规则层状结晶,导致压延铜箔在后续的电镀铜过程中容易产生表面粗糙的问题。压延铜箔通常用于挠性线路板,线路表面越粗糙,则电阻越大,相应的信号延迟越大,信号质量越差。本文研制了一种用于化学镀铜前处理工艺的微蚀液,改变压延铜箔的表面形貌,提高电镀后铜箔表面平整度,形成的表面粗糙度(Ra)低于50 nm,表面轮廓最大高度(Rz)低于200 nm,为后续工艺打下良好基础。

关键词：压延铜箔挠性线路板粗糙度微蚀液

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HPLC法检测6%吡嘧磺隆·丙草胺·二氯喹啉酸颗粒剂

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化工管理 2024年第7期 43-45页

作者：张平祁月月杨明君徐勇存金鑫雷浙江天丰生物科学有限公司检测中心浙江金华321000

采用高效液相色谱法,使用50 mm×4.6 mm C_(18)色谱柱,以甲醇+乙腈+0.05%磷酸水溶液为流动相,在254 nm(2 min后更改为230 nm)波长下对吡嘧磺隆·丙草胺·二氯喹啉酸颗粒剂进行分离和检测。经检测二氯喹啉酸、吡嘧磺隆、丙草胺在此分析... 详细信息

采用高效液相色谱法,使用50 mm×4.6 mm C_(18)色谱柱,以甲醇+乙腈+0.05%磷酸水溶液为流动相,在254 nm(2 min后更改为230 nm)波长下对吡嘧磺隆·丙草胺·二氯喹啉酸颗粒剂进行分离和检测。经检测二氯喹啉酸、吡嘧磺隆、丙草胺在此分析方法下具有良好的线性关系。吡嘧磺隆线性回归方程为y=3144x+2.8726,相关系数R^(2)=0.9999。丙草胺线性回归方程为y=426.78x-0.08,相关系数R^(2)=0.9994。二氯喹啉酸线性回归方程为y=5630.4x+51.736,相关系数R^(2)=1.0000。此检测方法具有线性关系好、精密度高、回收率高、检测速度快的特点,适用于该产品的定性定量检测。

关键词：二氯喹啉酸吡嘧磺隆丙草胺高效液相色谱法定性定量检测

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